It is now a widely accepted hypothesis that the glycosylation of asparagine residues in glycoproteins proceeds via an en bloc mechanism in which the oligosaccharide chain is preassembled on a polyisoprenoid carrier (dolichyl pyrophosphate) before being transferred to protein. Little is known concerning the regulation of dolichol-mediated glycosylation. Indirect evidence has been published suggesting that the level of dolichyl phosphate plays a role in controlling the rate of glycosylation. It is planned to investigate this possibility by employing as a model system the chick oviduct, in which the synthesis of glycoproteins can be controlled exogenously using estrogenic hormones. Dolichol-mediated glycosylation will be quantitated by monitoring the specific incorporation of radioactive mannose into oviduct glycoproteins in tissue mince. Dolichyl phosphate will be assayed directly using either high pressure liquid chromatography or a radioisotope dilution technique similar to that described for dolichol (Keller, R. K. and Adair, W. L., Biochim. et Biophys. Acta (1977 in press). It is also proposed to explore the mechanisms which control dolichyl phosphate levels. Both the rate of synthesis of dolichyl phosphate de novo (assayed in vitro as described by Grange, D. K. and Adair, W. L., Biochem. Biophys. Res. Commun. (1977) in press) and via phosphorylation of pre-existing free dolichol will be determined at various stages of glycoprotein induction. These studies should shed considerable light on the mechanism of regulation of glycoprotein synthesis.